Graphene is a two-dimensional nanostructure of covalently bonded carbon atoms and exhibits surprising mechanical, electrical, and thermal properties. Graphene flakes consist of single or several graphene sheets exfoliated from graphite. Graphene flakes have been reconstituted into bulky structures that have a modulus exceeding that of flexible graphite while possessing high strength.
A major challenge for graphene structures with high strength and toughness is to maintain the inherent active surface of graphene by preventing restacking of graphene tending to form close-packed layer structures. Single-layer graphene or a graphene flake has a wrinkled structure due to high area-to-thickness ratio thereof, but a graphene paper or composite including a large amount of graphene usually has a dense layer structure similar to graphite. The dense layered structure of graphene is an obstacle in achieving maximum mechanical properties owing to the short length of graphene that reduces the van der Waals force and tensile strength between graphene layers (by 1% or less).
There is no report on graphene composites including a considerable concentration of graphene while maintaining the inherent wrinkled structure of graphene. Little is also known about the development of fibers from graphene composites.